Since acrylonitrile-butadiene-styrene (hereinafter referred to as “ABS”) resin including styrene as a main raw material has properties such as stiffness, chemical resistance, impact resistance, and processability and exhibits superior secondary processing characteristics such as superior impact strength, mechanical properties, surface gloss, plateability, printability, and paintability, it may be used to produce products having various colors. However, sole use of ABS resin in components such as components of automobile interior and exterior materials requiring heat resistance, a transparent window of a washing machine requiring transparency, a cleaner dust cup, and transparent windows of office equipment is limited.
A method of using a polycarbonate resin to impart transparency has difficulties in being applied to large-sized components due to low chemical resistance and low-temperature impact resistance and poor processability. In addition, U.S. Pat. No. 3,787,522 and Japanese Unexamined Patent Application Publication No. Sho 63-42940 have attempted to provide impact resistance to a transparent polymethylmethacrylate resin, but satisfactory results were not obtained. In the case of European Patent No. 0 703 252 in which a HIPS (High Impact Polystyrene) resin was provided with transparency, transparency and processability were superior, but chemical resistance and scratch resistance were decreased.
In addition, a method of adding a maleimide-based or α-methyl styrene-based monomer, as a monomer having superior heat resistance, to a portion of ABS resin during polymerization, blending a heat-resistant copolymer resin including the monomer with an ABS resin, or adding an inorganic substance and the like has been developed to impart heat resistance.
However, since such a maleimide-based monomer has a problem that it is very difficult to control reaction temperature due to very high polymerization speed, there is a limitation in increasing the content of the maleimide-based monomer in a resin, and compatibility with an ABS resin and impact strength are decreased with increasing content of the monomer. In addition, since the α-methyl styrene monomer requires a long reaction time due to very slow polymerization speed, productivity is decreased, the molecular weight of a polymer is low, and pyrolysis easily occurs.
Therefore, there is a need for development of a thermoplastic resin satisfying all of heat resistance, transparency, and the like.